Heat exchanger element and applications thereof



Feb. 27, 1962 R. DEMALANDER 3,022,982

HEAT EXCHANGER ELEMENT AND APPLICATIONS THEREOF Filed Dec. 50, 1959 2 Sheets-Sheet 1 inveh'f f: e20 Janna/WK Feb. 27, 1962 R. DEMALANDER 3,022,982

HEAT EXCHANGER ELEMENT AND APPLICATIONS THEREOF Filed Dec. 30, 1959 2 Sheets-Sheet 2 mi E mug

3,022,982 HEAT EXCHANGER ELEMENT AND APPLICATIONS THEREOF Roger Demalander, Maidieres les Pout a Mousson,

rance, assignor to Compagnie de Pont-a-Mousson,

Nancy, France, a body corporate of France Filed Dec. 30, 1959, Ser. No. 863,009 Claims priority, application France Dec. 31, 1958 2 Claims. (Cl. 257-245) The present invention relates to heat exchanger elements for heating apparatus adapted for hot air heating of large premises.

Exchanger elements are already known in which the outer wall is entirely covered with spikes in order to generate in the gaseous fiuid turbulence's which promote the thermal exchange. Such known elements are generally used for a one way stream of the external air in the heating apparatus.

It is also known to provide tubular elements with outer fins, directed in accordance with the sense of flow of the air to be heated. Elements of this latter type are more particularly employed when the air circulated along the outer walls has its path of flow altered within the heating apparatus. Since it forces the gaseous fluid to flow along a definite path, this latter type of element leaves, in particular at the change of direction bends, wall areas outside said path and hence outside the thermal exchange. Such areas constitute dead zones.

The object of the present invention is an improved heat exchanger element having no such dead zones, for a hot-air heating apparatus wherein the direction of air flow is changeable.

In this improved element, which has walls forming a tubular duct for a heat exchange between the air to be heated circulated by convection around said element and hot combustion gases circulated inside the latter, the outer surfaces of the exchange-operative major walls are provided, on the one hand, with spikes in the areas where air which is licking said outer surfaces changes the direction of its flow and, on the other hand, with guide fins parallel to the longitudinal axis of the element outside said needled or spiked areas.

Owing to the combination of guide fins in the outer Surface portions of the exchanger on which one of the fluids (cg. air) flows in a straight path and of spikes in the areas where said fluid has the direction of its flow changed, it is found in practice that the thermal yield of the exchanger element shows a marked improvement.

A further object of the invention is a heating apparatus having at least one tubular element of the aforesaid improved type.

Further features of the invention will be apparent from the ensuing description with reference to the accompanying drawings to which the invention is in no way restricted and in which:

FIG. 1 is a longitudinal sectional view of a portion of an improved tubular element, according to the invention:

FIG. 2 is a diagrammatic sectional view on a smaller scale of a heat exchanger provided with such a tubular element shown from the outside; and

FIG. 3 is a view similar to that of FIG. 2 showing a heat exchanger provided with an alternative embodiment of the tubular element, according to the invention.

FIG. 4 is a view in perspective, with portions removed, of a tubular element according to the invention.

In the embodiment illustrated in FIGS. 1 and 2, the heat exchanger element E is adapted to be used on a heating apparatus of the type in which two cold air streams are simultaneously admitted along two horizontal opposite paths, follow an ascending path and, after 3,922,92 Patented Feb. 27, 1%62 2 having been heated, are subsequently evacuated to the outside along two opposite horizontal paths.

This element E essentially comprises a tubular body 1 having an axis X-.X of generally rectangular crosssection with rounded angles, and provided at the ends thereof with rectangular mounting flanges 2. The tubular body 1 has a plurality of inner fin banks 3 parallel to the axis X X along the entire width of the opposite operative major walls.

On the greater portion of the length of element E, ex- Cept on the end areas thereof, the outer surfaces of the operative walls of body 1 are provided with outer fin banks 4 which are also perpendicular to the axis XX. From one bank to another, these fins are arranged in a quincunx formation. Moreover, the tubular body, along its entire length including the aforesaid end regions, carries a median fin bank or row 5 arranged on the axial symmetry plane PP (FIG. 2).

In the end areas and in the portion extended beyond the outer fins 4, the outer faces of the major walls of body 1 additionally comprise a plurality of spikes 6 having the same height as the fins 4 and 5 and similarly arranged in a quincunx formation. In other words, the same area of the outer face of each major wall of body 1 carries thereon the same number of spikes 6 than that of fins i and 5.

The element E is enclosed in an outer casing 7 (FIG. 2) having a vertical axis XX coinciding with the trace of plane P--P, adapted to be located above a heat source, in the path of the fumes circulated in the direction shown by arrows 1.

The casing 7 comprises at the lower portion thereof two oppositely located horizontal tubular members 8 extending onto the element E opposite of the spikes 6, to ensure the admittance of the air to be heated in the direction of arrows f and f and, at the upper portion thereof, two similar tubular members 9 providing for the exit of hot air in the direction shown by arrows f and f The fumes follow an upward path inside the tubular body 1, while air is circulated between the element E and the outer casing 7. On either side of the axial symmetry plane P--P of the exchanger, the flow of air is as follows:

Upon arriving horizontally to the region of spikes 6., the cold air stream is divided into a plurality of fluid streamlets which leak in-between the spikes and surround them. A diffusion zone is thus formed. The air is accordingly in contact with the entire surface area of the tubular body 1 and the spikes 6 carried thereon, even in the medial area of the axial plane of symmetry. This air impinges the median fin bank 5 which obstructs its path and is thus deflected vertically, being subsequently canalized by the guide fins'd. Air flows then into the upper region of spikes 6, where further turbulence or eddying occurs to promote the heat exchange, prior to escaping through the tubular port 9.

Owing to the presence of spikes 6, there are no dead zones which are not swept by the air to be heated at the outer surface of the exchange element. Thus, the apparatus has an increased thermal yield.

According to the embodiment shown in FIG. 3, the median fin bank 5 extending into the spiked zone 6 to separate the latter into two parts of equal size, is omitted.

Both opposite air streams, upon being fed into the apparatus by the inlets 8, are divided in the inner region of the, spikes 6, impinge each other and ascend along the fins 4. They are again divided in the upper region of spikes 6 and are sucked in separately by the respective exit ports 9.

Reference can be had to FIG. 4 which illustrates, in perspective and with portions removed, a tubular element seasons '3 a 7 according to the invention; this element can be of the type shown in FIGS. 1 and 2 if the median fin bank extends into the spiked zones 6, or of the type shown in FIG. 3 if said bank 5 does not extend into said zones 6. It is to be understood that this invention is in no way limited by the embodiment described and illustrated, which are given merely by way of example.

Thus, the tubular elements designed in accordance with the invention can be assembled in any desired quantity to form a tubular bank.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. An air heating apparatus comprising in combination: a casing having the general shape of a parallelepiped; said casing having an axis and a wall including an inner face, a bottom axial ingress and a top axial egress for fumes heating the air, two lateral bottom air inlets symmetric and at right angle with respect to said axis and two lateral top air outlets symmetric and at right angle with respect to said axis; in said casing, an axial, centrally disposed, heat-exchange walled tubular element inside of which the fumes flow; said tubular element being spaced from the inner face of said casing intermediate the ends thereof and defining an air passageway between said tubular element and said inner face intermediate said ends and having two flat opposite end walls defining end portions situated above and below said air outlets and inlets respectively and being in fiuidtight relationship with said casing; two banks of pins located on said tubular element opposite said air inlets and outlets respectively andprojecting from said tubular element; and a bank of fins parallel to said axis, located on an intermediate portion of said tubular element between said end portions.

2. An air heating apparatus according to claim 1, in which said tubular element is provided with opposite median fin rows extending axially and aligned with a row of said fins to form a central partition of fins in said tubular element from one end to the other end thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,275,492 .Sterzing Aug. 13, 1918 2,004,252 Sorenson June 11, 1935 2,663,170 Gloyer Dec. 22, 1953 2,704,062 Beyerman Mar. 15, 1955 2,834,582 Kablitz May'13, 1958 FOREIGN PATENTS 744,963 Great Britain Feb. 15, 1956 

